Metabolome In 5-Fu Resistant Gastric Cancer Organoids

Recent advances in metabolomics have deepened our understandings of the roles that specific modes of metabolism play in the maintenance of stem cells. Several pieces of evidence have demonstrated that cancer stem cells (CSCs) play a key role in the acquisition of drug resistance. Organoid is a novel 3D cell culture system through using the specific niche factors in a dish and is believed to harbor abundant stem cells; cancer organoid could possibly be useful for scrutinizing CSC biology. In this study, we successfully established 5-FU resistant gastric cancer organoids (GCOs) from patient-derived specimens, which were further confirmed by significant changes in the expression of molecules related to 5-FU metabolism. We then performed metabolome analysis using 3 pairs of 5-FU resistant/ parental GCOs and 10 pairs of non-neoplastic gastric organoid/ GCOs generated from the same patients. PCA plotting revealed that 5-FU resistant GCOs showed a distinct signature compared to those of their parental GCOs and 10 pairs of non-neoplastic gastric organoid/ GCOs. Among various significant changes in the metabolic pathways, we focused on the excessive reliance on the energy from TAC cycle in 5-FU resistant GCO because the difference was specifically seen in the comparison between 5-FU resistant and parental GCOs: not found in the comparison between 10 pairs of non-neoplastic gastric organoid and GCOs. We examined IC50 value for Tigecyclin and VLX600, both of which have an inhibitory effect on TCA cycle, by MTT assay using 5-FU resistant GCO and 2 gastric cancer cell lines (MKN-45 and MKN-74). Although there was almost no difference in IC50 values for Tigecyclin and VLX600 between 2 gastric cell lines and their 5-FU resistant cells, IC50 for both of TCA cycle inhibitors in 5-FU resistant GCO was significantly lower compared to that in parental GCO. Further studies are ongoing in order to verify the significance of dependency on TCA cycle, which could potentially lead to the development of new therapy for 5-FU resistant gastric cancer. Citation Format: Naoya Sakamoto, Kazuhito Naka, Shoichi Ukai, Ririno Honma, Daiki Taniyama, Tsuyoshi Takashima, Ryota Maruyama, Kazuaki Tanabe, Hideki Ohdan, Wataru Yasui. Metabolome in 5-FU resistant gastric cancer organoids [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4762.